For the treatment of malignant tumor, surgical therapy, radiotherapy, and chemotherapy by an anticancer agent have been mainly used as of today. Diagnostic technology and clinical technology have markedly progressed, so that it is not impossible to treat malignant tumors.
However, at present, a ratio of malignant tumors occupied in a cause of death exceeds 30%, and development of a novel therapeutic method against malignant tumors has been desired. Thus, as a novel therapeutic method, development of gene therapy, immunotherapy, hyperthermia, etc. has been started.
Among the above-mentioned novel therapeutic methods for malignant tumors, hyperthermia is an old therapeutic method which has been carried out from ancient Greece and is a therapeutic method which utilizes a property that malignant tumor cells are weaker to heat than normal cells. That which has widely been used as the hyperthermia is a method in which a portion existing a tissue of malignant tumor is entirely heated to kill the malignant tumor cells which are weak against heat.
As a hyperthermia for malignant tumor, it has been known a method in which magnetic fine particles are used as an internal heating element, and the magnetic fine particles are heated by electromagnetic wave. In order to increase therapeutic effect by uniformly heating the malignant tumor tissue, it has been known to use magnetic magnetite as magnetic fine particles, and to prepare a magnetite cationic liposome (MCL) by coating the magnetite with a lipid membrane (liposome) having a positive charge to increase an intake efficiency of the magnetite into the malignant tumor cells since the surfaces of the malignant tumor cells are charged to negative and to use the same (Shinkai et al., Jpn. J. Hyperthermic Oncol., vol. 10, pp. 168-177 (1994) and Shinkai et al., Biotech. Appl. Biochem., vol. 21, pp. 125-137 (1994)).
A hyperthermia for malignant tumor has been attracted attention since it is a noninvasive therapeutic method, but this hyperthermia is difficult to completely treat various kinds of malignant tumors in many cases when it is used alone.
Accordingly, an improved hyperthermia which can treat various kinds of malignant tumors more effectively has been required.